CD mastering is the final touch after the recording & mixing process. You've recorded your song / album in a pro or home studio & it's been finally mixed. The music sounds great but you feel that it is sonically inferior to your favorite CD.
Your song mixes may not be consistently loud enough or well balanced. Your vocals may sound buried or in the contrary, too upfront. There may be too much low end or not enough.
There maybe some unwanted noise in your recordings.
These are only a few of the common problems we fix.